Historically, the pneumatic tire has been fabricated as a laminate structure of generally toroidal shape having beads, a tread, belt reinforcement, and a carcass. The tire is made of rubber, fabric, and steel. The manufacturing technologies employed for the most part involved assembling the many tire components from flat strips or sheets of material. Each component is placed on a building drum and cut to length such that the ends of the component meet or overlap creating a splice.
In the first stage of assembly the prior art carcass will normally include one or more plies, and a pair of sidewalls, a pair of apexes, an innerliner (for a tubeless tire), a pair of chafers and perhaps a pair of gum shoulder strips. Annular bead cores can be added during this first stage of tire building and the plies can be turned around the bead cores to form the ply turnups. Additional components may be used or even replace some of those mentioned above.
This intermediate article of manufacture would be cylindrically formed at this point in the first stage of assembly. The cylindrical carcass is then expanded into a toroidal shape after completion of the first stage of tire building. Reinforcing belts and the tread are added to this intermediate article during a second stage of tire manufacture, which can occur using the same building drum or work station.
This form of manufacturing a tire from flat components that are then formed toroidally limits the ability of the tire to be produced in a most uniform fashion. As a result, an improved method and apparatus has been proposed, the method involving building a tire sequentially on a core or toroidal body. The core or toroidal body rotates about its axis as tire components are applied layer by layer to the outer core surface. When the tire build procedure is completed on the core, the green tire will have a shape and dimension only slightly smaller than the finished tire. The aforementioned variances resulting from conventional drum expansion are thus eliminated. Building a tire on a core to a final tire shape, dimension, and uniformity therefore allows for improved quality control of the finished product.
Use of a tire building core in conventional tire construction improves the accuracy of tire component placement because the tire is built to a near final shape and dimension. Pursuant to industry convention, the core includes a plurality of segments that unite to form an annular tire building surface in one configuration, and collapse to facilitate removal of the core in a second configuration. The core is typically held together with separate latches on each segment. While working well, separately latching the segments is more complex, expensive, and time consuming than the industry desires. In addition, it is at times necessary to relocate the core assembly and tire during the tire manufacturing process. Conventional core assemblies provide no mechanism for facilitating a convenient and efficient relocation of the core assembly as required.
Accordingly, the industry remains in need of a multi-segment tire building core that assembles quickly and is readily transportable. The components of the core assembly should securely couple in a manner that ensures the unity of the core assembly throughout any necessary relocation. Moreover, the core assembly should maintain the structural integrity of the tire building surface during tire build operation.